The non-verbal numerical abilities identified in non-human animals as well as human infants and young children are hypothesized to represent biological and developmental precursors of adult humans'more sophisticated numerical and mathematical abilities. Information regarding the neural basis for the processing of number during childhood may therefore prove critical to our understanding of individual differences in mathematical abilities, including such disorders of mathematical abilities as acalculia and developmental dyscalculia. Numerical cognition and the perception of numerosity have been linked via functional neuroimaging studies of adults to activity in regions of parietal cortex including the inferior and superior parietal lobules, the angular gyri, and the horizontal segment of the intraparietal sulci. However, little is known about the neural correlates of number processing in children or about the changes in brain function that support the development of numerosity perception and numerical cognition during childhood. Likewise, the neurobiological basis of individual differences in mathematical abilities in children and adults remains poorly understood. The overarching goal of the proposed research is to characterize, using functional magnetic resonance imaging (fMRI), the patterns of change in brain activity associated with developmental changes in aspects of number perception and numerical cognition during early childhood. An additional goal is to identify potential correlations between individual differences in mathematical abilities and individual differences in patterns of developmental change in brain activity. By evaluating how the neural circuitry supporting number processing normally develops over the 4- to 8-year-old period, and how it differs from or is similar to that of adults, the proposed research will begin to explore systematically the longitudinal development and neural bases for the representation and manipulation of number. This project will set the stage for comparative studies of children with impairments in mathematical abilities. Moreover, this work will provide a methodological foundation for future work aimed at evaluating the neural mechanisms underlying successful educational interventions for remediation of deficits in mathematical abilities in children. Consistent with these goals, we will analyze the longitudinal fMRI data and laboratory and standardized measures of number processing and mathematics achievement to identify potential neural predictors of individual differences in math abilities in the children we scan. This research will inform our basic understand of how changes in the brain relate to developmental changes in the ways in which children perceive and think about numbers. This basic understanding, in turn, might inform our understanding of individual differences in math abilities. This program of research could eventually lead to improvements in math curriculum and intervention programs for children at risk for developing difficulties in learning math.This research will inform our basic understand of how changes in the brain relate to developmental changes in the ways in which children perceive and think about numbers. This basic understanding, in turn, will inform our understanding of individual differences in math abilities. This program of research could eventually lead to improvements in math curriculum and intervention programs for children at risk for developing difficulties in learning math.